AB0409 TIME TO FIRST REMISSION AND PREVALENCE OF SUSTAINED REMISSION AFTER ETANERCEPT BIOSIMILAR (ETA-B) OR ORIGINATOR (ETA-O) INITIATION IN RHEUMATOID ARTHRITIS (RA)
Authors: C. S Moura, D. Choquette, G. Boire, W. P. Maksymowych, L. Lukusa, L. Yan, M. G. Birck, S. Bernatsky
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> The first biosimilar etanercept (ETA-B) was approved in Canada in 2016, but real-world data comparing the effectiveness of ETA-B versus their equivalent originator (ETA-O) remains scarce. <h3>Objectives</h3> To compare time to remission throughout follow-up and sustained RA remission in the first 12 months. <h3>Methods</h3> We studied etanercept-naïve RA patients starting ETA-B or ETA-O between January 2015 and May 2022 from three prospective research cohorts related to the Early Undifferentiated Polyarthritis (Sherbrooke), RA Pharmacovigilance Program and Outcomes Research in Therapeutics (Edmonton), and RHUMADATA<sup>TM</sup> (Montreal) registries. We restricted analyses to RA patients with at least one follow-up visit after treatment initiation and with enough data to calculate remission. Remission was defined as Disease Activity Score 28-CRP or -ESR ≤2.6, Simplified Disease Activity Index ≤ 3.3, or Clinical Disease Activity Index ≤ 2.8. We used Cox regression to compare ETA-B versus ETA-O regarding time to first remission during follow-up (among those without remission at baseline) and logistic regression to assess sustained remission (remission in two consecutive visits) in the first 12 months of follow-up. Models were adjusted for sex, age, body mass index (BMI), RA duration, and smoking status at cohort entry. We also adjusted for high/moderate disease activity and the use of corticosteroids, methotrexate (MTX), or hydroxychloroquine (HCQ), all at etanercept initiation. <h3>Results</h3> We studied 150 RA patients initiating etanercept (65% on the biosimilar) between 2015-2022. Sex distribution was similar among ETA-B and ETA-O, but the biosimilar group has a longer disease duration and moderate/higher disease activity at baseline. Among 125 participants without remission at baseline, the median time to first remission was 8.7 months with ETA-B versus 14.5 with ETA-O. In the multivariate analysis (Table 1A), we were unable to detect a clear difference in time to achieve first remission when comparing ETA-B to ETA-O (hazard ratio, HR = 1.43, 95% confidence interval, CI 0.65-3.13). Obesity (BMI&gt;30) was negatively associated with the outcome. Sustained remission in the first 12 months of follow-up was observed in 16.3% of ETA-B initiators versus 17.3% with ETA-O. After multivariate analysis (Table 1B), we were unable to establish any clear difference between ETA-B versus ETA-O (OR 1.16, 95% CI 0.31-4.74). HCQ was positively associated with sustained remission within the first 12 months. <h3>Conclusion</h3> In this pooled analysis of three Canadian RA cohorts, we were unable to detect clear differences in achievement or sustained remission when comparing ETA-B and ETA-O. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Cristiano S Moura: None declared, Denis Choquette Speakers bureau: Amgen, Abbvie, Celltrion, Eli Lilly, Frezenius-Kabi, Inesss, Ministry of health (Québec), Pfizer, Novartis, Sandoz, Tevapharm., Consultant of: Amgen, Abbvie, Celltrion, Eli Lilly, Frezenius-Kabi, Inesss, Ministry of health (Québec), Pfizer, Novartis, Sandoz, Tevapharm., Grant/research support from: Rhumadata™ is supported by Abbvie, Amgen, Frezenius-Kabi, Pfizer, Sandoz, Tevapharm., Gilles Boire Speakers bureau: BMS Canada, Janssen Canada, Orimed, Viatris (honorarium for presentations), Consultant of: Advisory committees: Abbvie Canada, Janssen Canada, Lilly Canada, Mylan Canada, Novartis Canada, Samsung Bioepis, Sanofi Canada, Teva., Grant/research support from: Local PI in multicentric trials: Merck Canada, Pfizer Canada Unrestricted financial support for investigator-initiated initiatives: Lilly Canada, Pfizer Canada, Walter P Maksymowych Consultant of: Abbvie, Amgen, Boehringer, BMS, Celgene, Eli-Lilly, Galapagos, Janssen, Novartis, Pfizer, UCB, Grant/research support from: Abbvie, Eli-Lilly, Novartis, Pfizer, UCB., Luck Lukusa: None declared, Laura Yan: None declared, Marina G. Birck: None declared, Sasha Bernatsky: None declared.